Ethnic-specific associations of sleep duration and daytime napping with prevalent type 2 diabetes in postmenopausal women.

OBJECTIVE: The objective of this study was to evaluate ethnic differences in the associations of nighttime sleep and daytime napping durations with prevalent type 2 diabetes.

METHODS: Samples of White (n = 908), Filipina (n = 330), and Black (n = 371) community-dwelling, postmenopausal women aged 50-86 years were evaluated with cross-sectional data obtained during 1992-1999 including self-reported duration of nighttime sleep and daytime napping, behaviors, medical history, and medication use. The prevalence of type 2 diabetes was evaluated with a 2-h 75-g oral glucose tolerance test.

RESULTS: Overall, 10.9% of White, 37.8% of Filipina, and 17.8% of Black women had type 2 diabetes. Average sleep durations were 7.3, 6.3, and 6.6 h and napping durations were 16.8, 31.7, and 25.9 min for White, Filipina, and Black women, respectively. Sleep duration showed a significant (p < 0.01) nonlinear association with type 2 diabetes in Filipina women, with increased odds of diabetes at both low and high sleep durations independent of age, body mass index (BMI), triglyceride to high-density lipoprotein (HDL) ratio, hypertension, and daytime napping duration. Daytime napping duration was associated with type 2 diabetes only among White women; those napping ≥ 30 min/day had 74% (95% confidence interval (CI) = 10%, 175%) higher odds of diabetes compared to non-nappers independent of covariates including nighttime sleep duration.

CONCLUSIONS: Results suggest ethnic-specific associations of nighttime sleep and daytime napping durations with type 2 diabetes.